Showing papers in "Reproductive Biology and Endocrinology in 2004"
TL;DR: There is a dynamic interplay between pro- and anti-oxidant substances in human ejaculate and a threshold for ROS levels that may induce functional sperm ability or may lead to male infertility is unsolved.
Abstract: There is a dynamic interplay between pro- and anti-oxidant substances in human ejaculate. Excessive reactive oxygen species (ROS) generation can overwhelm protective mechanism and initiate changes in lipid and/or protein layers of sperm plasma membranes. Additionally, changes in DNA can be induced. The essential steps of lipid peroxidation have been listed as well as antioxidant substances of semen. A variety of detection techniques of lipid peroxidation have been summarized together with the lipid components of sperm membranes that can be subjected to stress. It is unsolved, a threshold for ROS levels that may induce functional sperm ability or may lead to male infertility.
601 citations
TL;DR: Subsequently, sequential, overlapping actions of progesterone, IFN tau, placental lactogen (PL) and growth hormone (GH) comprise a hormonal servomechanism that regulates endometrial gland morphogenesis and terminal differentiated function to maintain pregnancy in sheep.
Abstract: Establishment and maintenance of pregnancy results from signaling by the conceptus (embryo/fetus and associated extraembryonic membranes) and requires progesterone produced by the corpus luteum (CL). In most mammals, hormones produced by the trophoblast maintain progesterone production by acting directly or indirectly to maintain the CL. In domestic animals (ruminants and pigs), hormones from the trophoblast are antiluteolytic in that they act on the endometrium to prevent uterine release of luteolytic prostaglandin F2 alpha (PGF). In cyclic and pregnant sheep, progesterone negatively autoregulates expression of the progesterone receptor (PR) gene in the endometrial luminal (LE) and superficial glandular epithelium (GE). Available evidence in cyclic sheep indicates that loss of the PR is closely followed by increases in epithelial estrogen receptors (ER) and then oxytocin receptors (OTR), allowing oxytocin to induce uterine release of luteolytic PGF pulses. In pregnant sheep, the conceptus trophoblast produces interferon tau (IFN tau) that acts on the endometrium to inhibit transcription of the ER alpha gene directly and the OTR gene indirectly to abrogate development of the endometrial luteolytic mechanism. Subsequently, sequential, overlapping actions of progesterone, IFN tau, placental lactogen (PL) and growth hormone (GH) comprise a hormonal servomechanism that regulates endometrial gland morphogenesis and terminal differentiated function to maintain pregnancy in sheep. In pigs, the conceptus trophoblast produces estrogen that alters the direction of PGF secretion from an endocrine to exocrine direction, thereby sequestering luteolytic PGF within the uterine lumen. Conceptus estrogen also increases expression of fibroblast growth factor 7 (FGF-7) in the endometrial LE that, in turn, stimulates proliferation and differentiated functions of the trophectoderm, which expresses the FGF-7 receptor. Strategic manipulation of these physiological mechanisms can offer therapeutic schemes to improve uterine capacity, conceptus survival and reproductive health.
392 citations
TL;DR: First trimester trophoblasts express differential gelatinase secretion profile according to the gestational week, and in JAR and early troPHoblasts (6–8 w) MMP-2 is the main gelatinase and the key enzyme in trophoblast invasion.
Abstract: The aim of this study was to examine the invasiveness of first trimester trophoblasts according to the secretion profile of MMP-2 and -9 at different gestational stages, and to test the similarity between primary trophoblast cell-culture and the JAR choriocarcinoma cell-line. First trimester trophoblasts were divided into two groups: 6–8 weeks (early) and 9–12 w (late) of gestation. The two trophoblast groups and JAR cells were cultured in medium, with various concentrations of forskolin and Epidermal Growth Factor (EGF). Proteolytic activity was detected by zymography and invasiveness was assessed by Matrigel invasion assay. Student's T-test was used for statistical analysis. In 6–8 w trophoblast, proMMP-2 was only slightly dominant over proMMP-9 (53.2% vs. 46.8% respectively), whereas in 9–12 w, proMMP-9 was clearly dominant over proMMP-2 (61.7% vs.38.3% respectively). In JAR cells proMMP-2 was strongly dominant (90.2% vs.9.8% respectively). In JAR cells forskolin significantly increased proMMP-2 and -9 secretion (128.5% +/- 12 and 183.2% +/- 27.9 of control, respectively). EGF had a dual effect on JAR cells: at 8 ng/ml both proMMP-2 and -9 were increased (133.5% +/-15 and 223.9% +/- 32.4 of control, respectively) while at 80 ng/ml both proMMP-2 and -9 were decreased (65.1% +/- 18.3 and 66.6% +/- 37 of control, respectively). Forskolin significantly increased both proMMP-2 and -9 secretion in 6–8 w and 9–12 w trophoblasts (125.9% +/- 6.3,128.4% +/- 6.4; 169.7% +/- 20.3, 120.3% +/- 4.5 of control, respectively). EGF also significantly increased both proMMP-2 and -9 secretion in 6–8 w and 9–12 w trophoblasts (141.22% +/- 14.8, 138.8% +/- 10.3; 168.3% +/- 18.2, 117.3 +/- 3.8 of control, respectively). Both forskolin and EGF increased trophoblast cells invasiveness in all groups. The invasive ability of trophoblast cells, induced by forskolin, was reduced by MMP-2 antibody in: JAR cells, 6–8 w and 9–12 w trophoblasts. Likewise trophoblast invasion induced by EGF was reduced by MMP-2 antibody in all groups. However the invasive ability induced by forskolin or EGF was inhibited by MMP-9 antibody only in trophoblasts from 9–12 w. First trimester trophoblasts express differential gelatinase secretion profile according to the gestational week. In JAR and early trophoblasts (6–8 w) MMP-2 is the main gelatinase and the key enzyme in trophoblast invasion. Thereafter in late first trimester trophoblasts (9–12 w), both MMP-2 and -9 participate in trophoblast invasion.
336 citations
TL;DR: Studies of MUC1 expression and function in reproductive tissues with particular emphasis on the uterus are summarized and current knowledge of the mechanisms of M UC1 gene regulation, metabolic processing and potential signal transducing functions will be presented.
Abstract: MUC1 is a large, transmembrane mucin glycoprotein expressed at the apical surface of a variety of reproductive tract epithelia. Functions attributed to MUC1 include those generally associated with mucins such as lubrication and hydration of cell surfaces as well as protection from microorganisms and degradative enzymes. In addition, MUC1 is an effective inhibitor of both cell-cell and cell-extracellular matrix interactions in both normal and malignant contexts. Moreover, a series of recent studies has shown that the highly conserved cytoplasmic tail of MUC1 interacts specifically with a series of important signal transducing molecules including β-catenin, Grb2 and erbB family members. MUC1 expression in normal epithelia can be quite dynamic, varying in response to steroid hormone or cytokine influences. Following malignant transformation, MUC1 often becomes highly overexpressed, loses its apical restriction, and displays aberrant glycosylation and altered mRNA splice variants. Regulation of MUC1 expression can occur at the transcriptional level. In addition, post-translational regulation of cell surface expression occurs via the activity of cell surface proteases or "sheddases" that release soluble forms of the large ectodomains. This review will briefly summarize studies of MUC1 expression and function in reproductive tissues with particular emphasis on the uterus. In addition, current knowledge of the mechanisms of MUC1 gene regulation, metabolic processing and potential signal transducing functions will be presented.
281 citations
TL;DR: The prolactin (PRL) and growth hormone (GH) gene families represent species-specific expansions of pregnancy-associated hormones/cytokines.
Abstract: The prolactin (PRL) and growth hormone (GH) gene families represent species-specific expansions of pregnancy-associated hormones/cytokines In this review we examine the structure, expression patterns, and biological actions of the pregnancy-specific PRL and GH families
273 citations
TL;DR: A heuristic model is constructed for the mechanisms and molecules involved in capacitation/acrosome reaction and it is shown that the protein phosphorylation especially at tyrosine residues is one of the most important events that occur during capacitation.
Abstract: Capacitation is an important physiological pre-requisite before the sperm cell can acrosome react and fertilize the oocyte. Recent reports from several laboratories have amply documented that the protein phosphorylation especially at tyrosine residues is one of the most important events that occur during capacitation. In this article, we have reviewed the data from our and other laboratories, and have constructed a heuristic model for the mechanisms and molecules involved in capacitation/acrosome reaction.
253 citations
TL;DR: Alterations in syndecan expression, leading to either overexpression or loss of expression, both of which take place in tumor cells, may have dramatic effects on tumor cell invasion.
Abstract: Anchorage of cells to "heparin" – binding domains that are prevalent in extracellular matrix (ECM) components is thought to occur primarily through the syndecans, a four-member family of transmembrane heparan sulfate proteoglycans that communicate environmental cues from the ECM to the cytoskeleton and the signaling apparatus of the cell. Known activities of the syndecans trace to their highly conserved cytoplasmic domains and to their heparan sulfate chains, which can serve to regulate the signaling of growth factors and morphogens. However, several emerging studies point to critical roles for the syndecans' extracellular protein domains in tumor cell behavior to include cell adhesion and invasion. Although the mechanisms of these activities remain largely unknown, one possibility involves "co-receptor" interactions with integrins that may regulate integrin function and the cell adhesion-signaling phenotype. Thus, alterations in syndecan expression, leading to either overexpression or loss of expression, both of which take place in tumor cells, may have dramatic effects on tumor cell invasion.
252 citations
TL;DR: These findings, together with very recent evidence from animal models, suggest that preeclampsia is associated with abnormal placental production of vasculogenic/angiogenic substances that reach the maternal circulation with the potential to produce at least a subset of the clinical signs of this syndrome.
Abstract: The placenta is a remarkable organ. In normal pregnancy its specialized cells (termed cytotrophoblasts) differentiate into various specialized subpopulations that play pivotal roles in governing fetal growth and development. One cytotrophoblast subset acquires tumor-like properties that allow the cells to invade the decidua and myometrium, a process that attaches the placenta to the uterus. The same subset also adopts a vascular phenotype that allows these fetal cells to breach and subsequently line uterine blood vessels, a process that channels maternal blood to the rest of the placenta. In the pregnancy complication preeclampsia, which is characterized by the sudden onset of maternal hypertension, proteinuria and edema, cytotrophoblast invasion is shallow and vascular transformation incomplete. These findings, together with very recent evidence from animal models, suggest that preeclampsia is associated with abnormal placental production of vasculogenic/angiogenic substances that reach the maternal circulation with the potential to produce at least a subset of the clinical signs of this syndrome. The current challenge is to build on this knowledge to design clinically useful tests for predicting, diagnosing and treating this dangerous disorder.
211 citations
TL;DR: Differentiation of primitive granulosa and germ cells from the bipotent mesenchymal cell precursors of TA in adult human ovaries represents a most sophisticated adaptive mechanism created during the evolution of female reproduction.
Abstract: Recent reports indicate that functional mouse oocytes and sperm can be derived in vitro from somatic cell lines. We hypothesize that in adult human ovaries, mesenchymal cells in the tunica albuginea (TA) are bipotent progenitors with a commitment for both primitive granulosa and germ cells. We investigated ovaries of twelve adult women (mean age 32.8 ± 4.1 SD, range 27–38 years) by single, double, and triple color immunohistochemistry. We show that cytokeratin (CK)+ mesenchymal cells in ovarian TA differentiate into surface epithelium (SE) cells by a mesenchymal-epithelial transition. Segments of SE directly associated with ovarian cortex are overgrown by TA, forming solid epithelial cords, which fragment into small (20 micron) epithelial nests descending into the lower ovarian cortex, before assembling with zona pellucida (ZP)+ oocytes. Germ cells can originate from SE cells which cover the TA. Small (10 micron) germ-like cells showing PS1 meiotically expressed oocyte carbohydrate protein are derived from SE cells via asymmetric division. They show nuclear MAPK immunoexpression, subsequently divide symmetrically, and enter adjacent cortical vessels. During vascular transport, the putative germ cells increase to oocyte size, and are picked-up by epithelial nests associated with the vessels. During follicle formation, extensions of granulosa cells enter the oocyte cytoplasm, forming a single paranuclear CK+ Balbiani body supplying all the mitochondria of the oocyte. In the ovarian medulla, occasional vessels show an accumulation of ZP+ oocytes (25–30 microns) or their remnants, suggesting that some oocytes degenerate. In contrast to males, adult human female gonads do not preserve germline type stem cells. This study expands our previous observations on the formation of germ cells in adult human ovaries. Differentiation of primitive granulosa and germ cells from the bipotent mesenchymal cell precursors of TA in adult human ovaries represents a most sophisticated adaptive mechanism created during the evolution of female reproduction. Our data indicate that the pool of primary follicles in adult human ovaries does not represent a static but a dynamic population of differentiating and regressing structures. An essential mission of such follicular turnover might be elimination of spontaneous or environmentally induced genetic alterations of oocytes in resting primary follicles.
211 citations
TL;DR: It is argued that a definitive epitheliochorial placenta is a secondary specialization and that it evolved twice,once in the Laurasiatheria and once in the lemurs and lorises.
Abstract: Based on the number of tissues separating maternal from fetal blood, placentas are classified as epitheliochorial, endotheliochorial or hemochorial. We review the occurrence of these placental types in the various orders of eutherian mammals within the framework of the four superorders identified by the techniques of molecular phylogenetics. The superorder Afrotheria diversified in ancient Africa and its living representatives include elephants, sea cows, hyraxes, aardvark, elephant shrews and tenrecs. Xenarthra, comprising armadillos, anteaters and sloths, diversified in South America. All placentas examined from members of these two oldest superorders are either endotheliochorial or hemochorial. The superorder Euarchontoglires includes two sister groups, Glires and Euarchonta. The former comprises rodents and lagomorphs, which typically have hemochorial placentas. The most primitive members of Euarchonta, the tree shrews, have endotheliochorial placentation. Flying lemurs and all higher primates have hemochorial placentas. However, the lemurs and lorises are exceptional among primates in having epitheliochorial placentation. Laurasiatheria, the last superorder to arise, includes several orders with epitheliochorial placentation. These comprise whales, camels, pigs, ruminants, horses and pangolins. In contrast, nearly all carnivores have endotheliochorial placentation, whilst bats have endotheliochorial or hemochorial placentas. Also included in Laurasiatheria are a number of insectivores that have many conserved morphological characters; none of these has epitheliochorial placentation. Consideration of placental type in relation to the findings of molecular phylogenetics suggests that the likely path of evolution in Afrotheria was from endotheliochorial to hemochorial placentation. This is also a likely scenario for Xenarthra and the bats. We argue that a definitive epitheliochorial placenta is a secondary specialization and that it evolved twice, once in the Laurasiatheria and once in the lemurs and lorises.
205 citations
TL;DR: The glands gradually regress over the first trimester, but still communicate with the intervillous space until at least 10 weeks, which means they could provide an important source of nutrients, growth factors and cytokines for the feto-placental unit.
Abstract: Background
The maternal circulation to the human placenta is not fully established until 10–12 weeks of pregnancy. During the first trimester the intervillous space is filled by a clear fluid, in part derived from secretions from the endometrial glands via openings in the basal plate. The aim was to determine the activity of the glands throughout the first trimester, and to identify components of the secretions.
TL;DR: The extracellular matrix (ECM) is now appreciated as a key regulator of cell and tissue behavior and genetic approaches clearly demonstrate critical requirements for genes encoding ECM components or modifiers of ECM in a wide variety of processes in vivo.
Abstract: The extracellular matrix (ECM) is now appreciated as a key regulator of cell and tissue behavior. Support for this notion has been derived from correlative studies demonstrating large changes in the composition and distribution of extracellular matrix components during tissue development, differentiation and in response to hormone/growth factor/cytokine influences. In addition, a variety of functional studies demonstrate ECM-dependent cellular responses in vitro while genetic approaches clearly demonstrate critical requirements for genes encoding ECM components or modifiers of ECM, e.g., metalloproteases, in a wide variety of processes in vivo.
TL;DR: Decades of studies that have helped unearth the mechanisms that contribute to the tumor-like phenotype of human trophoblast cells are reviewed, and the invasive cytotrophoblastic cell type and the tumor cell type are compared.
Abstract: Trophoblast cells of the human placenta proliferate, migrate, and invade the pregnant uterus and its vasculature in order to nourish the developing fetus, in a way that is imitated by malignant tumors. Many similarities exist between embryo implantation and the growth of cancer cells. We begin this article by reviewing decades of studies that have helped unearth the mechanisms that contribute to the tumor-like phenotype of human trophoblast cells. Interestingly, these attributes are only transient in nature, with stringent spatial and temporal confines. The importance of intrinsic molecular controls that effectively circumscribe the extent and duration of trophoblast incursion, becomes increasingly evident in abnormal pregnancies that are characterized by aberrant trophoblast proliferation/invasion. We summarize and discuss the significance of abnormalities in these regulatory mechanisms, and finally, speculate about the use of human trophoblastic cells as model systems for the study of a variety of cellular processes. While on one hand, human placental cells are bestowed with a capacity to proliferate indefinitely and invade extensively, on the other, these cells are also replete with mechanisms to regulate these tumor-like attributes and eventually progress to a senescent apoptotic state. This is therefore, a 'well-behaved' tumor. The comparison in the present review is between the invasive cytotrophoblastic cell type and the tumor cell type.
TL;DR: It is noteworthy that gene ablation in mice has so far failed to identify obligatory initial molecular events in mice, and there is good progress on identifying gene networks required for early placentation.
Abstract: Implantation of the embryo in the uterus is a critical and complex event and its failure is widely considered an impediment to improved success in assisted reproduction. Depending on whether placentation is invasive or superficial (epitheliochorial), the embryo may interact transiently or undergo a prolonged adhesive interaction with the uterine epithelium. Numerous candidate interactions have been identified, and there is good progress on identifying gene networks required for early placentation. However no molecular mechanisms for the epithelial phase are yet firmly established in any species. It is noteworthy that gene ablation in mice has so far failed to identify obligatory initial molecular events.
TL;DR: This review will survey what is currently know concerning PCa interaction with the extracellular matrix (ECM) and the roles of factors within the tumor and ECM microenvironments that contribute to metastasis.
Abstract: Prostate cancer (PCa) is no exception to the multi-step process of metastasis. As PCa progresses, changes occur within the microenvironments of both the malignant cells and their targeted site of metastasis, enabling the necessary responses that result in successful translocation. The majority of patients with progressing prostate cancers develop skeletal metastases. Despite advancing efforts in early detection and management, there remains no effective, long-term cure for metastatic PCa. Therefore, the elucidation of the mechanism of PCa metastasis and preferential establishment of lesions in bone is an intensive area of investigation that promises to generate new targets for therapeutic intervention. This review will survey what is currently know concerning PCa interaction with the extracellular matrix (ECM) and the roles of factors within the tumor and ECM microenvironments that contribute to metastasis. These will be discussed within the context of changes in expression and functional heterodimerization patterns of integrins, changes in ECM expression and reorganization by proteases facilitating invasion. In this context we also provide a brief summary of how growth factors (GFs), cytokines and regulatory signaling pathways favor PCa metastasis to bone.
TL;DR: The identification of P-regulated genes and gene pathways in the primate endometrium is expected to be an important first step in elucidating the cellular processes necessary for the development of a receptive environment for implantation.
Abstract: Background: In the endometrium the steroid hormone progesterone (P), acting through its nuclear receptors, regulates the expression of specific target genes and gene networks required for endometrial maturation. Proper endometrial maturation is considered a requirement for embryo implantation. Endometrial receptivity is a complex process that is spatially and temporally restricted and the identity of genes that regulate receptivity has been pursued by a number of investigators. Methods: In this study we have used high density oligonucleotide microarrays to screen for changes in mRNA transcript levels between normal proliferative and adequate secretory phases in Rhesus monkey artificial menstrual cycles. Biotinylated cRNA was prepared from day 13 and days 21–23 of the reproductive cycle and transcript levels were compared by hybridization to Affymetrix HG-U95A arrays. Results: Of ~12,000 genes profiled, we identified 108 genes that were significantly regulated during the shift from a proliferative to an adequate secretory endometrium. Of these genes, 39 were upregulated at days 21–23 versus day 13, and 69 were down-regulated. Genes up-regulated in Pdominant tissue included: secretoglobin (uteroglobin), histone 2A, polo-like kinase (PLK), spermidine/spermine acetyltransferase 2 (SAT2), secretory leukocyte protease inhibitor (SLPI) and metallothionein 1G (MT1G), all of which have been previously documented as elevated in the Rhesus monkey or human endometrium during the secretory phase. Genes down-regulated included: transforming growth factor beta-induced (TGFBI or BIGH3), matrix metalloproteinase 11 (stromelysin 3), proenkephalin (PENK), cysteine/glycine-rich protein 2 (CSRP2), collagen type VII alpha 1 (COL7A1), secreted frizzled-related protein 4 (SFRP4), progesterone receptor membrane component 1 (PGRMC1), chemokine (C-X-C) ligand 12 (CXCL12) and biglycan (BGN). In addition, many novel/unknown genes were also identified. Validation of array data was performed by semiquantitative RT-PCR of two selected up-regulated genes using temporal (cycle day specific) endometrial cDNA populations. This approach confirmed up-regulation of WAP four-disulfide core domain 2 (WFDC2) and SLPI during the expected window of receptivity. Conclusion: The identification of P-regulated genes and gene pathways in the primate endometrium is expected to be an important first step in elucidating the cellular processes necessary for the development of a receptive environment for implantation.
TL;DR: Both proinflammatory cytokines, TNF alpha and IL-1, have significant roles in normal testicular functions as well as in certain testicular pathologies.
Abstract: This review will focus the roles of TNF-alpha, IL-1 alpha, and IL-1 beta in the mammalian testis and in two testicular pathologies, testicular torsion and orchitis. TNF alpha in the testis is produced by round spermatids, pachytene spermatocytes, and testicular macrophages. The type 1 TNF receptor has been found on Sertoli and Leydig cells and numerous studies suggest a paracrine mode of action for TNF alpha in the normal testis. IL-1 alpha has been reported to be produced by Sertoli cells, testicular macrophages, and possibly postmeiotic germ cells. IL-1 receptors have been reported on Sertoli cells, Leydig cells, testicular macrophages, and germ cells suggesting both autocrine and paracrine functions. While these proinflammatory cytokines have important roles in normal testicular homeostasis, an elevation of their expression can lead to testicular dysfunctions. Testicular torsion is a clinical pathology with results in testicular ischemia and surgical intervention is often required for reperfusion. A pivotal role for IL-1beta in the pathology of testicular torsion has been recently described whereby an increase in IL-1beta production after reperfusion of the testis is correlated with the activation of the stress-related kinase, c-jun N-terminal kinase, and ultimately resulting in neutrophil recruitment to the testis and germ cell apoptosis. In autoimmune orchitis, on the other hand, TNF alpha produced by T-lymphocytes and macrophages of the testis has been implicated in the development and progression of the disease. Thus, both proinflammatory cytokines, TNF alpha and IL-1, have significant roles in normal testicular functions as well as in certain testicular pathologies.
TL;DR: The goal of this chapter is to summarize the current views regarding the natural process of follicle selection in primates and to discuss how this process may be amplified to produce a greater number of oocytes.
Abstract: During the follicular phase of the primate menstrual cycle, a single follicle usually matures to the preovulatory stage and releases its oocyte for fertilization and the potential establishment of pregnancy. In assisted reproductive technology procedures, it is desirable to override the natural process of follicle selection to produce many oocytes that are capable of being fertilized and undergoing normal embryo development. The goal of this chapter is to summarize the current views regarding the natural process of follicle selection in primates and to discuss how this process may be amplified to produce a greater number of oocytes.
TL;DR: Observations suggest that egg protein fragments accumulate in the CF during the post-ovulatory period and could therefore be used to detect egg quality defects associated with oocyte post-OVulatory ageing.
Abstract: In fish, oocyte post-ovulatory ageing is associated with egg quality decrease. During this period, eggs are held in the body cavity where they bath in a semi-viscous liquid known as coelomic fluid (CF). CF components are suspected to play a role in maintaining oocyte fertility and developmental competence (egg quality). However, CF proteic composition remains poorly studied. Thus rainbow trout CF proteome was studied during the egg quality decrease associated with oocyte post-ovulatory ageing. High resolution two-dimensional gel electrophoresis was used to analyze the proteome of rainbow trout (Oncorhynchus mykiss) CF in relationship with the egg quality decrease associated with oocyte post-ovulatory ageing. A first experiment was performed using CF pools originating from 17 females sampled at ovulation as well as 7, 14 and 21 days later. These observations were verified using a second set of CF pools originating from 22 females sampled 5 and 16 days following ovulation. Approximately 200 protein spots of 10–105 kDa molecular mass and 3–10 pI were detected in CF samples. Several protein spots, while undetected at the time of ovulation, exhibited a progressive and strong accumulation in CF during post-ovulatory ageing. After silver-staining and Matrix-Assisted Laser Desorption Time Of Flight (MALDI-TOF) mass spectrometer analysis, some of these protein spots were identified as lipovitellin II fragments. These observations suggest that egg protein fragments accumulate in the CF during the post-ovulatory period and could therefore be used to detect egg quality defects associated with oocyte post-ovulatory ageing.
TL;DR: Clustering analysis demonstrated that trophoblast-cell-specific molecules such as placental lactogens (PLs), prolactin-related proteins (PRPs), interferon-tau, and adhesion molecules apparently all play pivotal roles in the preparation needed for implantation, since their expression was remarkably enhanced during the pre-implantation period.
Abstract: After fertilization, embryo development involves differentiation, as well as development of the fetal body and extra-embryonic tissues until the moment of implantation. During this period various cellular and molecular changes take place with a genetic origin, e.g. the elongation of embryonic tissues, cell-cell contact between the mother and the embryo and placentation. To identify genetic profiles and search for new candidate molecules involved during this period, embryonic gene expression was analyzed with a custom designed utero-placental complementary DNA (cDNA) microarray. Bovine embryos on days 7, 14 and 21, extra-embryonic membranes on day 28 and fetuses on days 28 were collected to represent early embryo, elongating embryo, pre-implantation embryo, post-implantation extra-embryonic membrane and fetus, respectively. Gene expression at these different time points was analyzed using our cDNA microarray. Two clustering algorithms such as k-means and hierarchical clustering methods identified the expression patterns of differentially expressed genes across pre-implantation period. Novel candidate genes were confirmed by real-time RT-PCR. In total, 1,773 individual genes were analyzed by complete k-means clustering. Comparison of day 7 and day 14 revealed most genes increased during this period, and a small number of genes exhibiting altered expression decreased as gestation progressed. Clustering analysis demonstrated that trophoblast-cell-specific molecules such as placental lactogens (PLs), prolactin-related proteins (PRPs), interferon-tau, and adhesion molecules apparently all play pivotal roles in the preparation needed for implantation, since their expression was remarkably enhanced during the pre-implantation period. The hierarchical clustering analysis and RT-PCR data revealed new functional roles for certain known genes (dickkopf-1, NPM, etc) as well as novel candidate genes (AW464053, AW465434, AW462349, AW485575) related to already established trophoblast-specific genes such as PLs and PRPs. A large number of genes in extra-embryonic membrane increased up to implantation and these profiles provide information fundamental to an understanding of extra-embryonic membrane differentiation and development. Genes in significant expression suggest novel molecules in trophoblast differentiation.
TL;DR: There is a decrease in GR levels in human cervix at parturition, and there is an increase of factors such as NFkappaB, PAF-R, COX-1 andCOX-2, suggesting that they may participate in the sequence of events leading to the final cervical ripening.
Abstract: Cervical ripening is an inflammatory reaction. The glucocorticoid receptor (GR) mediates glucocorticoid anti-inflammatory reactions, whereas nuclear factor (NF)kappaB is a key pro-inflammatory transcription factor. Prostaglandins as well as platelet activating factor (PAF) are inflammatory mediators. Inducible nitric oxide synthase (iNOS) regulates the level of nitric oxide (NO) in response to various inflammatory stimuli. We hypothesize that a changed biological response to glucocorticoids could be a mechanism regulating the inflammatory events resulting in cervical ripening. We monitored GR and NFkappaB, prostaglandin synthases cyclooxygenase (COX)-1 and -2, iNOS, as well as the PAF-receptor (PAF-R) in the uterine cervix from term pregnant women (with unripe cervices) before the onset of labor (TP), immediately after parturition (PP), as compared to non-pregnant (NP), using immunohistochemistry and RT-PCR. The GR protein was detected by immunohistochemistry in the nuclei of stroma and squamous epithelium (SQ). Stromal GR staining was increased in TP as compared to the NP group and decreased again after parturition. GR staining in SQ was decreased after parturition as compared to term. NFkappaB was present in SQ and glandular epithelium (GE), stroma and vascular endothelium. Increased nuclear NFkappaB staining was observed postpartum as compared to term pregnancy in stroma and GE. Stromal immunostaining for COX-1 as well as COX-2 was increased in the TP and PP groups as compared to the NP, and GE displayed an intensely increased COX-2 immunostaining at term and postpartum. Stromal PAF-R immunostaining was highest at term, while it was greatly increased in GE postpartum. No difference in the immunostaining for iNOS was found between the groups. RT-PCR showed a predominance of GRalpha to GRbeta mRNA in cervical tissue. The COX-2 mRNA level was increased in the PP group as compared to the TP group. There is a decrease in GR levels in human cervix at parturition. Concomitantly there is an increase of factors such as NFkappaB, PAF-R, COX-1 and COX-2, suggesting that they may participate in the sequence of events leading to the final cervical ripening.
TL;DR: The possibility that periconceptional supplementation with folate and vitamin B12 might lower the incidence of miscarriage in women planning a pregnancy is discussed.
Abstract: The pathogenesis of human spontaneous abortion involves a complex interaction of several genetic and environmental factors. The firm association between increased homocysteine concentration and neural tube defects (NTD) has led to the hypothesis that high concentrations of homocysteine might be embryotoxic and lead to decreased fetal viability. There are several genetic polymorphisms that are associated with defects in folate- and vitamin B12-dependent homocysteine metabolism. The methylenetetrahydrofolate reductase (MTHFR) 677C>T and 1298A>C polymorphisms cause elevated homocysteine concentration and are associated with an increased risk of NTD. Additionally, low concentration of vitamin B12 (cobalamin) or transcobalamin that delivers vitamin B12 to the cells of the body leads to hyperhomocysteinemia and is associated with NTD. This effect involves the transcobalamin (TC) 776C>G polymorphism. Importantly, the biochemical consequences of these polymorphisms can be modified by folate and vitamin B12 supplementation. In this review, I focus on recent studies on the role of hyperhomocysteinemia-associated polymorphisms in the pathogenesis of human spontaneous abortion and discuss the possibility that periconceptional supplementation with folate and vitamin B12 might lower the incidence of miscarriage in women planning a pregnancy.
TL;DR: Low-frequency EA stimulation with a strong intensity increases OBF in rats with steroid-induced PCO whereas less strong intensity induces similar changes in control rats, which suggests that the responses of OBF to EA are mediated via the ovarian sympathetic nerves.
Abstract: Maintenance of ovarian blood flow (OBF) is suggested to be important for regular ovulation in women with polycystic ovaries (PCO). The purpose of the present study was to investigate whether electro-acupuncture (EA) of different frequencies and intensities can improve the OBF of anaesthetized rat in the animal model of PCO. PCO was experimentally induced by a single intramuscular (i.m.) injection of estradiol valerate (EV) in rats. Control rats were given i.m. injection of oil. The involvement of the two ovarian sympathetic nerves; superior ovarian nerve (SON) and plexus ovarian nerve (OPN), in OBF responses was elucidated by severance of SON and OPN in both control and PCO rats. How systemic circulatory changes affect OBF was evaluated by continuous recording of the blood pressure. OBF was measured on the surface of the ovary-using laser Doppler flowmetry. Acupuncture needles were inserted bilaterally into the abdominal and hind limb muscles and connected to an electrical stimulator. Two frequencies – 2 Hz (low) and 80 Hz (high) – with three different intensities – 1.5, 3, and 6 mA – were applied for 35 s. Low-frequency EA at intensities of 3 and 6 mA elicited significant increases in OBF in the Control group compared to baseline. In the PCO group the increases in OBF were significant only when stimulating with low-frequency EA at 6 mA. After severance of the ovarian sympathetic nerves, the increased response of OBF that had been induced by low-frequency EA in both the Control and PCO group was abolished, indicating that the OBF response is mediated via the ovarian sympathetic nerves. High-frequency EA at 6 mA significantly decreased OBF and mean arterial blood pressure (MAP) in the Control group compared to baseline. In the PCO group, the same stimulation produced similar decreases in MAP, but not in OBF. Low-frequency EA stimulation with a strong intensity (6 mA) increases OBF in rats with steroid-induced PCO whereas less strong intensity (3 mA) induces similar changes in control rats. Severance of the ovarian sympathetic nerves, abolish this OBF increase in both study groups, which suggests that the responses of OBF to EA are mediated via the ovarian sympathetic nerves.
TL;DR: This work has shown that mice brain damage could be mediated through a final common pathway, which includes over-stimulation of excitatory amino acid receptor, over-production of vascularization/angiogenesis, pro-inflammatory cytokines, neurotrophic factors and apoptotic-inducing factors.
Abstract: Intrauterine infection is considered as one of the major maternal insults during pregnancy. Intrauterine infection during pregnancy could lead to brain damage of the developmental fetus and offspring. Effects on the fetal, newborn, and adult central nervous system (CNS) may include signs of neurological problems, developmental abnormalities and delays, and intellectual deficits. However, the mechanisms or pathophysiology that leads to permanent brain damage during development are complex and not fully understood. This damage may affect morphogenic and behavioral phenotypes of the developed offspring, and that mice brain damage could be mediated through a final common pathway, which includes over-stimulation of excitatory amino acid receptor, over-production of vascularization/angiogenesis, pro-inflammatory cytokines, neurotrophic factors and apoptotic-inducing factors.
TL;DR: Using the in vivo baboon model, it is shown that Chorionic Gonadotropin, as the major trophoblast derived signal, not only rescues the corpus luteum but also modulates the uterine environment in preparation for implantation.
Abstract: Implantation is a complex spatio-temporal interaction between the growing embryo and the mother, where both players need to be highly synchronized to be able to establish an effective communication to ensure a successful pregnancy. Using our in vivo baboon model we have shown that Chorionic Gonadotropin (CG), as the major trophoblast derived signal, not only rescues the corpus luteum but also modulates the uterine environment in preparation for implantation. This response is characterized by an alteration in both the morphological and biochemical activity in the three major cell types: luminal and glandular epithelium and stromal fibroblasts. Furthermore, CG and factors from the ovary have a synergistic effect on the receptive endometrium. Novel local effects of CG which influence the immune system to permit the survival of the fetal allograft and prevent endometrial cell death are also discussed in this review. An alternate extracellular signal-regulated kinase (ERK) activation pathway observed in epithelial endometrial cells and the possibility of differential expression of the CG/LH-R isoforms during gestation, open many questions regarding the mechanism of action of CG and its signal transduction pathway within the primate endometrium.
TL;DR: ES and TS cells from the mouse and other species are beginning to provide insights into the changes in gene expression that accompany lineage specification and the subsequent post-specification events that lead to functional trophoblast derivatives.
Abstract: A zone of trophoblast specification is established when the embryo is a morula, presumably reflecting a unique combination of transcription factors in that zone of cells and the influence of various environmental cues and growth factors on them. A key first step in this process of specification is the down-regulation of Oct4, a transcription factor that acts as a negative regulator of trophoblast specification and of genes normally up-regulated as the trophectoderm first forms. The transcription factors believed to have a positive association with trophectoderm specification have been inferred primarily in two ways: by their expression patterns in embryos, ES cells and TS cells and by the consequences of gene disruption on embryonic development. Many of these transcription factors also control the expression of genes characteristically expressed in trophoblast but not in the epiblast, primitive endoderm and their derivatives. ES and TS cells from the mouse and other species are beginning to provide insights into the changes in gene expression that accompany lineage specification and the subsequent post-specification events that lead to functional trophoblast derivatives.
TL;DR: The involvement of leptin in the nutritional control of reproduction in birds is demonstrated and it is shown that leptin action on the ovary probably controls follicular hierarchy through the regulation of steroidogenesis.
Abstract: In hens, the ovarian follicles committed to ovulation are arranged in an ordered follicular hierarchy. In standard broiler breeders hens genetically selected for high growth rate the reproductive function is clearly dysfunctional. Feed restriction is needed during reproductive development to limit the formation of excessive numbers of ovarian yellow follicles arranged in multiple hierarchies. To determine whether leptin is involved in the nutritional and reproductive interactions controlling follicular hierarchy in hens, blood leptin levels and ovarian expression of the leptin receptor mRNA were determined during follicle maturation in three chicken lines; a slow growing broiler "Label" genotype without reproductive dysfunction, a fast growing "Standard" genotype fed ad libitum or restricted and a fast growing "Experimental" line with intermediate reproductive performance levels. Whereas expression of the leptin receptor mRNA did not change in the theca, it clearly decreased with follicular differentiation in the granulosa of slow growing hens. In fast growing standard hens fed ad libitum and presenting significant reproductive dysfunction, the decrease was disrupted and dramatic up-regulation of granulosa cell expression of the leptin receptor was observed. On the other hand, feed restriction decreased the overall level of expression of the leptin receptor mRNA and restored the decrease with follicular growth. The level of expression of the leptin receptor probably modulates the action of leptin on follicular differentiation. Since blood leptin and other metabolic factors were not affected by the genotype or by nutritional state, the factors involved in the regulation of leptin receptor gene expression remain to be determined. This study demonstrates the involvement of leptin in the nutritional control of reproduction in birds. Leptin action on the ovary probably controls follicular hierarchy through the regulation of steroidogenesis.
TL;DR: HE2 C-terminal peptides can inhibit E. coli macromolecular synthesis and suggest an additional mechanism of bacterial killing supplementary to membrane permeabilization, further evidence for their membrane dependent mechanism of antibacterial action.
Abstract: The HE2 gene encodes a group of isoforms with similarities to the antimicrobial beta-defensins. We demonstrated earlier that the antimicrobial activity of HE2 proteins and peptides is salt resistant and structure dependent and involves permeabilization of bacterial membranes. In this study, we further characterize the antimicrobial properties of HE2 peptides in terms of the structural changes induced in E. coli and the inhibition of macromolecular synthesis. E. coli treated with 50 micro g/ml of HE2alpha, HE2beta1 or HE2beta2 peptides for 30 and 60 min were visualized using transmission and scanning electron microscopy to investigate the impact of these peptides on bacterial internal and external structure. The effects of HE2alpha, HE2beta1 and HE2beta2 on E. coli macromolecular synthesis was assayed by incubating the bacteria with 2, 10 and 25 micro g/ml of the individual peptides for 0–60 min and measuring the incorporation of the radioactive precursors [methyl-3H]thymidine, [5-3H]uridine and L-[4,5-3H(N)]leucine into DNA, RNA and protein. Statistical analyses using Student's t-test were performed using Sigma Plot software. Values shown are Mean ± S.D. E. coli treated with HE2alpha, HE2beta1 and HE2beta2 peptides as visualized by transmission electron microscopy showed extensive damage characterized by membrane blebbing, thickening of the membrane, highly granulated cytoplasm and appearance of vacuoles in contrast to the smooth and continuous membrane structure of the untreated bacteria. Similarly, bacteria observed by scanning electron microscopy after treating with HE2alpha, HE2beta1 or HE2beta2 peptides exhibited membrane blebbing and wrinkling, leakage of cellular contents, especially at the dividing septa, and external accumulation of fibrous materials. In addition, HE2alpha, HE2beta1 and HE2beta2 peptides inhibited E. coli DNA, RNA and protein synthesis. The morphological changes observed in E. coli treated with epididymal HE2 peptides provide further evidence for their membrane dependent mechanism of antibacterial action. HE2 C-terminal peptides can inhibit E. coli macromolecular synthesis, suggesting an additional mechanism of bacterial killing supplementary to membrane permeabilization.
TL;DR: The mouse study of Johnson et al. may suggest that the prosimian primates are not the only mammals to exhibit mitotically active germ cells in adult ovaries, and the dogma is to be debunked and a new one accepted.
Abstract: The mouse study of Johnson et al. (Nature 2004, 428: 145-150) may suggest that the prosimian primates are not the only mammals to exhibit mitotically active germ cells in adult ovaries. If the dogma is to be debunked and a new one accepted, at least in the mouse, it is sure to be challenged and tested, as should all dogma.
TL;DR: These findings in sheep are consistent with TGF-beta potentially being an important autocrine regulator of thecal cell function and possibly a paracrine regulator of ovarian cell function at various development stages.
Abstract: Recently, several members of the transforming growth factor-beta (TGF-beta) superfamily have been shown to be essential for regulating the growth and differentiation of ovarian follicles and thus fertility. Ovaries of neonatal and adult sheep were examined for expression of the TGF-betas 1–3 and their receptors (RI and RII) by in situ hybridization using ovine cDNAs. The effects of TGF-beta 1 and 2 on proliferation and differentiation of ovine granulosa cells in vitro were also studied. The expression patterns of TGF-beta 1 and 2 were similar in that both mRNAs were first observed in thecal cells of type 3 (small pre-antral) follicles. Expression of both mRNAs continued to be observed in the theca of larger follicles and was also present in cells within the stroma and associated with the vascular system of the ovary. There was no evidence for expression in granulosa cells or oocytes. Expression of TGF-beta 3 mRNA was limited to cells associated with the vascular system within the ovary. TGFbetaRI mRNA was observed in oocytes from the type 1 (primordial) to type 5 (antral) stages of follicular growth and granulosa and thecal cells expressed this mRNA at the type 3 (small pre-antral) and subsequent stages of development. The TGFbetaRI signal was also observed in the ovarian stroma and vascular cells. In ovarian follicles, mRNA encoding TGFbetaRII was restricted to thecal cells of type 3 (small pre-antral) and larger follicles. In addition, expression was also observed in some cells of the surface epithelium and in some stromal cells. In granulosa cells cultured for 6 days, both TGF-beta 1 and 2 decreased, in a dose dependent manner, both the amount of DNA and concentration of progesterone. In summary, mRNA encoding both TGF-beta 1 and 2 were synthesized by ovarian theca, stroma and cells of the vascular system whereas TGF-beta 3 mRNA was synthesized by vascular cells. Luteinizing granulosa cells also responded to both TGF-beta 1 and beta 2 in vitro. These findings in sheep are consistent with TGF-beta potentially being an important autocrine regulator of thecal cell function and possibly a paracrine regulator of ovarian cell function at various development stages.